Niacin is a B-vitamin that is commonly used to treat high cholesterol and other conditions such as pellagra, a disease caused by niacin deficiency. According to the Mayo Clinic [2], niacin may cause side effects such as flushing, itching, and gastrointestinal distress. However, these side effects are usually mild and go away on their own after a short period. Alcohol is not known to worsen niacin side effects [1].

In fact, alcohol can interfere with the body's ability to absorb and use niacin, which can lead to a deficiency of this important nutrient. According to the Mount Sinai Health Library [3], chronic alcohol consumption can cause a deficiency of niacin, as well as other B-vitamins. This can lead to a condition known as alcoholic pellagra, which can cause symptoms such as skin rashes, digestive problems, and mental confusion.

In conclusion, alcohol is not known to worsen niacin side effects. However, chronic alcohol consumption can interfere with the body's ability to absorb and use niacin, which can lead to a deficiency of this important nutrient. If you are taking niacin supplements, it is important to talk to your doctor about your alcohol consumption and any other medications you may be taking to ensure that you are getting the right amount of this essential nutrient.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/ALCOHOL
[2] https://www.mayoclinic.org/drugs-supplements-niacin/art-20364984
[3] https://www.mountsinai.org/health-library/supplement/vitamin-b3-niacin